1,720,959 research outputs found
Effects of hyperoxic exposure on signal transduction pathways in the lung
No full textExposure to supraphysiological concentrations of oxygen is often applied in clinical practice to enhance oxygenation in acute or chronic lung injury. However, hyperoxic exposure is associated with increased reactive oxygen species production, which can be toxic to pulmonary endothelial and alveolar epithelial cells. Oxidative stress activates the pathways of the mitogen-activated protein kinases family: extracellular signal-regulated kinase (ERK1/2), C-Jun-terminal protein kinase (JNK1/2), and p38 kinase. Several studies have suggested that ERK activation in lung cells has a protective effect in response to hyperoxia, through stimulation of DNA repair and antioxidant mechanisms, and prolonged cell survival. Conversely, JNK1/2 and p38 kinase have been most frequently reported to have roles in induction of apoptotic responses. Moreover, exogenous factors, such as ATP, retinoic acid, substance P, thioredoxin, inosine and laminin, can have cytoprotective effects against hyperoxia-induced cell damage, through promotion of ERK activation and/or limiting JNK and p38 involvemen
Spexin is expressed in the carotid body and is upregulated by postnatal hyperoxia exposure.
No full textSpexin is a recently identified peptide which is expressed in many different endocrine and nervous tissues. Due to the absence of data regarding spexin expression in the carotid body, the first aim of the present study was to investigate, through immunohistochemistry and Real-Time PCR, the expression and distribution of spexin in the rat and human carotid body. Moreover, the carotid body is known to undergo various structural and functional modifications in response to hyperoxic stimuli during the first postnatal period. Thus, we also evaluated if hyperoxia during the first postnatal weeks may produce changes in the spexin expression. Materials consisted of carotid bodies obtained at autopsy from five human adult subjects and sampled from 10 six-weeks old Sprague-Dawley rats. Five rats were maintained in normoxia for the first six postnatal weeks; five rats were exposed to 60% hyperoxia for 2 weeks and then maintained in normoxia for other 4 weeks. Diffuse anti-spexin immunoreactivity was found in type I cells of both humans and rats. No spexin immunoreactivity was visible in the type II cells. Hyperoxia exposure during the first 2 weeks of postnatal life caused a reduction of volume in the carotid body still apparent after 4 weeks of normoxia. Using real-time PCR, spexin expression was 6-7 times higher in hyperoxia-exposed rats than in normoxia-exposed ones. The expression of spexin in type I cells suggests a possible modulator role in peripheral chemoreception. Moreover, the ascertained role of spexin in the regulation of cell proliferation in other tissues (e.g., adrenal gland cortex) suggests a possible role of spexin also in the hyperoxia-induced plasticity of the carotid body
Decellularization of rat and human omentum to develop novel scaffolds to be recellularized with adipose derived stem cells. In: LXV Congresso della Società Italiana di Anatomia e Istologia, Padova, 2011.
No full textDecellularization of rat and human omentum to develop novel scaffolds for regenerative medicine. In: 34° Congresso Nazionale della Sopcietà Italiana di Istochimica. San Benedetto del Tronto, 7-9 giugno 2011.
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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